Properties of milk protein-stabilized oil-in-water emulsions are determined by the structure and surface rheology of the adsorbed layer at the oil-water interface. Analysis of the segment density profiles normal to the surface shows differences in structure between adsorbed layers of disordered casein and globular whey protein. Systematic studies of stability and rheology of mode oil-in-water emulsion systems made with milk proteins as sole emulsifiers give insight into the relation between adsorbed layer properties and the bulk emulsion stability. Colloidal interactions between adsorbed layers on different surfaces can be inferred from an analysis of dynamic collisions or protein-coated emulsion droplets in shear flow using the new colloidal particle scattering technique. The role of competitive adsorption on emulsion properties can be derived from experiments on systems containing mixtures of milk proteins and small-molecule surfactants. The aggregated gel network properties are sensitive to the balance of weak and strong interparticle interactions. In heat-set whey protein emulsion gels, the rheological behaviour is especially sensitive to surfactant type and concentration.
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